Matlab postset method sample fails - matlab

Question

I'm trying to call a function right after I change some properties of an object in Matlab. I went to the documentation and found this sample code:
classdef PropListener < handle
properties (SetObservable, AbortSet)
PropOne
PropTwo
end
methods
function obj = PropListener(evtobj)
if nargin > 0
addlistener(evtobj,'PropOne','PostSet',#PropListener.handlePropEvents);
addlistener(evtobj,'PropTwo','PostSet',#PropListener.handlePropEvents);
end
end
end
methods (Static)
function handlePropEvents(src,evnt)
switch src.Name
case 'PropOne'
display('I was here!');
case 'PropTwo'
display('I was here too!');
end
end
end
end
I saved this into a file, went to the console and tryed
test1=PropListener
test1.PropOne=1
and it doesn't show the "I was here!" message. The rest works perfectly.
After some debuging, I found 2 problems:
1 - It calls the constructor method without arguments, therefore
if(argin>0)
returns always false and it never creates the listeners.
2 - If I remove the if/end structure, when I call the constructor
test1 = PropListener
Matlab returns "Error using PropListener (line 9)
Not enough input arguments."
(line 9 is the line with the following statement)
addlistener(evtobj,'PropOne','PostSet',#PropListener.handlePropEvents);
Now, if I remove the whole constructor method and call
addlistener(evtobj,'PropOne','PostSet',#PropListener.handlePropEvents);
on the command line, everything works, but I would have to remember to call that line while writing my scripts, and I don't want to run that risk.
I'd like to know how could I implement this postset feature, and any help would be greatly appreciated.
Thanks in advance,